Tyler Tessier was charged with murdering Lauren Wallen — a social studies teacher at Wilde Lake High School — after her body was discovered in a shallow grave in the woods of Damascus, Montgomery County Police Chief Thomas Manger said at a press conference.

The pair was last seen together captured on surveillance video at a grocery store near Wallen’s home on Sept. 2. She may have been killed the next day, the chief said.

A family member said they received a troubling text from her phone on Sept. 4. Police determined Tessier sent the chilling message.

Tyler Tessier (at the podium) speaks at a press conference on the disappearance of Laura Wallen in Montgomery County, Maryland, on Monday.

(Montgomery County Police via Per)

Wallen, 31, was reported missing after failing to show up to school the next day.

Tessier admitted to driving her car and removing the tags in the Columbia area. Her car was discovered at an apartment complex on Sept. 7.

He managed to get rid of Wallen’s license and iPhone, Manger said.

Tyler Tessier, Lauren Wallen’s boyfriend, tears up and is comforted by Wallen’s mother and father, Gwen and Mark Wallen, during a press conference on Sept. 11, 2017, in Montgomery County, Maryland.

(The Baltimore Sun)

Tessier called an acquaintance to help him “clean up a mess,” and drive him to Baltimore, but the plot failed, Manger added. He was living in three different locations during the week and police questioned the residents, the chief said.

He, who was fighting back tears at a press conference Monday, held Wallen’s mother hand and at one point was comforted by her father. Wallen’s family had offered a $25,000 reward for information leading to her whereabouts.